1 Field of the Invention
The present invention is directed to a method and apparatus for rapid screening of potential reactants, catalysts, and associated process-conditions and, more specifically, to a method and apparatus for rapid combinatorial screening of potential reactants and catalysts in mixed phase reaction systems.
2. Discussion of Related Art
Since its introduction in 1970, combinatorial chemistry has become a popular research tool among scientists in many fields. Combinatorial screening for biological activity has been prevalent in the pharmaceutical industry for nearly twenty years and, more recently, combinatorial screening for improved catalysts for the bulk chemical industries has enjoyed increasing popularity.
Early efforts in combinatorial screening of liquid phase reactions have focused on catalyst screening. Before the application of the combinatorial approach, catalyst testing was traditionally accomplished in bench scale or larger pilot plants in which feed to a continuous flow reactor was contacted with a catalyst under near steady state reaction conditions. This type of test system can be difficult to reproduce at the micro-scale required for combinatorial chemistry. Rapid combinatorial screening of reactants, catalysts, and associated process conditions requires that a large number of reactions or catalytic systems be tested simultaneously, while still providing a meaningful correlation between test results and eventual performance in a production-scale reactor.
Thus, there has been a lag in the development of combinatorial screening for production scale reactions. One reason has been the difficulty in emulating large-scale reactions at the micro-scale necessary for combinatorial work. In particular, special problems can arise for reactions that are significantly dependent on mass transport rates or flow configuration. For example, reactions may require that a liquid phase be saturated with a gaseous reactant for substantial phase transfer. This can be difficult to consistently reproduce for multiple samples on a small scale.
Furthermore, most combinatorial work to date has focused on xe2x80x9csolid phasexe2x80x9d reactions. It is known that a wide variety of organic reactions can be carried out on substrates immobilized on resins. However, a substantial number of production scale reactions are xe2x80x9cliquid phasexe2x80x9d or xe2x80x9cmixed phase,xe2x80x9d and are typically carried out in continuous flow reactor systems.
A Finally, many combinatorial systems are highly complex and therefore may require significant effort and expense to be optimized for individual experiments. For many applications, it would be preferable to have a simple, compact apparatus which would be suitable for bench-top experiments and yet enable high-throughput chemical screening utilizing a variety of reaction formats.
As the demand for bulk chemicals has continued to grow, new and improved methods of producing more product with existing resources are needed to supply the market. However, the identities of additional effective reactants and catalyst systems for these processes continue to elude the industry. What are needed are new and improved methods and devices suitable for rapid screening of potential reactants, catalysts, and associated process conditions.
Accordingly, the present invention is directed to a method and apparatus for rapid screening of multiphase reactant systems. In one exemplary embodiment, the apparatus includes a reaction substrate having a plurality of substrate reservoirs adapted to receive a reactant system at least partially embodied in a liquid. A first heating source maintains the reactant system at a first temperature. A head plate is positioned relative to the reaction substrate such that a closed headspace is formed above the substrate reservoirs. The head plate includes a second heating source to maintain the head plate at a second temperature higher than the first temperature.
An exemplary method of the invention includes providing a plurality of substrate reservoirs and introducing a reactant system at least partially embodied in a liquid into individual substrate reservoirs. A headspace is provided to maintain the reactant system at a defined pressure and atmosphere and to avoid condensation upon heating of the liquid reactant system. A gaseous reactant may be included in the headspace atmosphere.